Switch mode power supplies are widely used in a variety of applications to convert alternating current (AC) electricity to one or more electrically isolated direct current (DC) outputs. The technology used for switch mode designs has improved substantially over the past decade allowing for smaller and more efficient designs. As design footprints have shrunk and power conversion efficiency has improved, many new packaging options have become feasible. Power supply customers are, consequently, demanding an ever increasing array of packaging and mounting options. These options include, but are not limited to, open frame packaging, cage frame packaging, U-channel packaging, table top/desk top packaging, wall mount packaging, module packaging, din rail packaging, chassis mount packaging, and rack mount packaging.
An open frame is comprised of simply a rectangular printed circuit board containing power supply circuitry. The board typically contains a plurality of mounting holes, preferably, at each corner of the board. The mounting holes provide a means to directly mount the board to the desired chassis or packaging configuration. In some embodiments, one or more studs or stand-offs are integrally formed with the chassis so as to facilitate mounting the printed circuit board within the chassis of electrical equipment.
The foregoing open frame may be coupled to a cage frame or a Faraday cage. A Faraday cage is an enclosure formed by conducting material, preferably a metallic material, that is used to shield external static electrical fields from a power supply. With printed circuit boards, Faraday cages are used to screen out electromagnetic interference generated by the power supply associated with the board. Typically, the Faraday cage is sized to fits over an open frame power supply, when the open frame is mounted in accordance with the above.
An open frame may also be mounted within a U-channel type package or configuration. U-channel packaging is typically comprised of a “U” shaped metal frame adapted to receive a printed circuit board. This metal frame is usually a single solid frame with a plurality of mounting holes contained at its periphery. In many cases, the frame is used to provide an electrical ground plane beneath the power supply. It is also often used as a heat sink for the power supply.
A printed circuit board may also be provided within an enclosure for a table top or desktop packaging. Table top or desktop packaging is typically comprised of a plastic enclosure containing a printed circuit board or open frame with an AC cable or connector on an input side of the enclosure and an DC cable or connector on the output side of the enclosure. A typical application is the external power supply for a notebook or laptop computer. By removing the power supply from the computer, the computer designer can create a smaller computer, can separate the computer from the heat and electromagnetic interference created by the power supply, and can simplify re-design cycles since the AC to DC conversion device does not have to be included in the safety approval process for the computer.
The open frame may also be mounted within a wall mount. A wall mount is and an external power supply designed for mounting directly on an AC outlet. To this end the wall mount converts the AC current of an electrical outlet to DC current that may be used in the accompanying device.
Similar to the wall mount is a module. A module is a power supply packaged for mounting directly on a printed circuit board. It typically has metal posts designed to be soldered directly to a printed circuit board. This approach is often used for power converters that adjust from one DC voltage to one or more lower DC voltages. It is also used for small AC to DC converters.
An open frame may also be mounted on a DIN rail. Although not limited thereto, a DIN rails is typically a standardized 35 mm wide metal rail with hat-shaped cross section. It is widely used for mounting circuit breakers and industrial control equipment inside equipment racks.
A chassis mount and a rack mount are types of mounts for open frames that are usually within a cabinet or other similar enclosure. Both structures are similar in that they are typically comprised of a flat metal sheet secured within the cabinet or similar enclosure wherein the flat sheet has a plurality of grooves or cutouts adapted to receive the open frame.
In addition to the basic packaging styles described above, there are many other options available. Most of these relate to different ways to remove heat, connect to or from the power supply, or reduce electromagnetic interference.
A key consequence of the variety of packaging options above is that there are often multiple versions of the power supply circuit reproduced on similar, but different, printed circuit boards. Each board is specifically designed to fit into one particular package or mounting configuration such that the open frames are not interchangeable between different configurations. While this will tend to optimize the design of each particular power supply and package combination, it greatly adds to the cost and complexity of a product line. In addition to the increased cost to design and produce multiple circuit boards, this approach adds cost and complexity since each printed circuit board must be designed, tested, and approved by the appropriate safety agencies. Finally, multiple versions of the printed circuit board also increases distribution costs since many similar parts must be held in inventory to fully stock the distribution channel.
Accordingly, a design is needed within the art for manufacturing a packaging frame than may be utilized in any of the foregoing packaging configurations. Such a design would have an equivalent optimization of design across each packaging structure, while reducing the cost and complexity of variations within the product lines. More importantly, costs will be further reduced because of the decreased need for producing multiple circuit boards for each particular use.
The present invention address the foregoing needs.